import { NgModule } from '@angular/core';

@NgModule({
  declarations: [], // components your module owns.
  imports: [], // other modules your module needs.
  providers: [], // providers available to your module.
  bootstrap: [] // bootstrap this root component.
})
export class MyModule {}

This is an empty module containing no declarations, imports, providers, or components to bootstrap. Use this a reference.

// app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpModule } from '@angular/http';
import { MyRootComponent } from './app.component';

@NgModule({
  declarations: [MyRootComponent],
  imports: [BrowserModule, HttpModule],
  bootstrap: [MyRootComponent]
})
export class MyModule {}

MyRootComponent is the root component packaged in MyModule. It is the entry point to your Angular 2 application.

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { MyModule }               from './app.module';

platformBrowserDynamic().bootstrapModule( MyModule );

In this example, MyModule is the module containing your root component. By bootstrapping MyModule your Angular 2 app is ready to go.

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';

import { AppComponent }  from './app.component';

@NgModule({
  imports: [ BrowserModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

We can statically bootstrap an application by taking the plain ES5 Javascript output of the generated factory classes. Then we can use that output to bootstrap the application:

import { platformBrowser } from '@angular/platform-browser';
import { AppModuleNgFactory } from './main.ngfactory';

// Launch with the app module factory.
platformBrowser().bootstrapModuleFactory(AppModuleNgFactory);

This will cause the application bundle to be much smaller, because all the template compilation was already done in a build step, using either ngc or calling its internals directly.